It is common to provide an integrated circuit, or a circuit formed of discrete components, in a single sealed package having a standardized terminal configuration (e.g., ball grid array, in-line pins, surface mount leads, etc.). The terminals of the package are typically then soldered to a printed circuit board along with other packages and components.
Relevant factors in a package design include size, terminal count, heat dissipation, current/voltage requirements, and electrical/magnetic interference issues.
To reduce the size of an electrical system, it is known to stack packages on top of each other, where the bottom package includes bottom terminals, for being soldered to a printed circuit board, and top terminals for being soldered to the terminals of the upper package. The bottom package has vias leading from its top terminals to internal circuitry or to the bottom terminals on the bottom package. This is also referred to as a 3-dimensional package.
For certain applications, such as high power applications, a more robust structure is needed for stacked packages. For such high power applications, such as a 20 A-100 A switching voltage regulator, it is desirable to provide very low impedance current paths to minimize heat and voltage drop, as well as provide good thermal paths to air and to a metal core printed circuit board. Also, certain components, such as inductors and transformers, should be separated from other circuits for minimizing magnetic coupling and noise.
Therefore, what is needed is a more robust package that solves some of the existing problems with conventional stacked packing technology.